The present invention relates generally to improvements in measuring and testing methods and equipment and relates particularly to an improved method and apparatus for determining the cell depth or condition of the surface of a printing, embossing or ink-metering roll having a surface provided with recesses or cells.
In many image-producing devices such as for printing on paper films, foils, fabrics and other webs there are employed rolls provided with cells or small recesses corresponding to the desired density or image, such rolls including flexo anilox rolls, machine engraved, roto-gravure coating, printing and applicator rolls, embossing rolls and the like. The effectiveness and condition of these ink metering and/or imaging rolls depends on the condition of the engraved roll surface which in turn depends on the depth of recesses or cells. As the roll surface cells or recesses diminish in depth below a predetermined value the quality, resolution and faithfulness of the reproduction produced by the roll is reduced until it is at an inferior and unacceptable level and the roll surface is no longer satisfactory. If the roll is employed after this unsatisfactory condition is reached the resulting product is of inferior quality and of less or no value. It is accordingly highly undesirable to employ printing, embossing and similar rolls after the recess or cell depth has reached a predetermined minimum value and in order to avoid this occurance it is highly desirable to determine the roll surface cell depth and hence the condition of this surface for further use and the available further usefulness thereof in producing acceptable reproduction.